What antibiotic eye drops are used to treat bacterial conjunctivitis (pink eye)?

Antibiotic Eye Drops for Bacterial Conjunctivitis (Pink Eye)

First-Line Treatment Recommendation

For mild bacterial conjunctivitis, use any broad-spectrum topical antibiotic eye drop (such as polymyxin B/trimethoprim, erythromycin ointment, or azithromycin) for 5-7 days, as the American Academy of Ophthalmology states no clinical evidence suggests superiority of any particular agent for mild cases. 1, 2

Treatment Algorithm Based on Severity

Mild Bacterial Conjunctivitis

• Choose the most convenient or least expensive antibiotic since efficacy is equivalent among agents 1
• Recommended options include:
  • Polymyxin B/trimethoprim (1 drop four times daily for 7 days) 3, 4
  • Erythromycin ointment (applied to eyelid margins) 1
  • Azithromycin 1.5% (1 drop twice daily for 3 days) - offers superior convenience 5
  • Tobramycin 0.3% (1 drop every 2 hours for 2 days, then 4 times daily for 5 days) 1, 5
• A 5-7 day course accelerates clinical and microbiological remission by days 2-5, reduces transmissibility, and allows earlier return to school/work 1

Moderate to Severe Bacterial Conjunctivitis

• Reserve fluoroquinolones for moderate to severe cases with copious purulent discharge, pain, and marked inflammation 1, 2
• Recommended fluoroquinolones:
  • Moxifloxacin 0.5% (1 drop three times daily for 7 days) 6, 7
  • Ciprofloxacin 0.3% (dosing per FDA label) 8, 9
  • Ofloxacin 1, 2
  • Gatifloxacin 1
• Obtain conjunctival cultures and Gram staining before initiating treatment if gonococcal infection is suspected 1

Contact Lens Wearers

• Use fluoroquinolones specifically due to higher risk of Pseudomonas infection 1, 2

Special Situations Requiring Systemic Antibiotics

Gonococcal Conjunctivitis

• Topical antibiotics alone are insufficient - systemic therapy is mandatory 10, 1, 2
• Ceftriaxone 250 mg IM single dose (adults) or 25-50 mg/kg IM (children, not to exceed 250 mg) 10
• Add saline lavage to promote comfort and faster resolution 1, 2
• Treat concurrently for chlamydia with azithromycin 1 g orally single dose 10

Chlamydial Conjunctivitis

• Systemic antibiotics required - topical therapy alone is inadequate 1, 2
• Azithromycin 1 g orally single dose OR Doxycycline 100 mg orally twice daily for 7 days 10, 2
• For neonates: Erythromycin base or ethylsuccinate 50 mg/kg/day divided into four doses for 14 days 10, 1

MRSA Conjunctivitis

• May require compounded topical vancomycin as MRSA is resistant to many commercially available topical antibiotics including aminoglycosides 1

Comparative Efficacy Data

Moxifloxacin vs. Polymyxin B/Trimethoprim

• Moxifloxacin demonstrates significantly faster cure rates: 81% complete resolution at 48 hours versus 44% with polymyxin B/trimethoprim (P=0.001) 6
• Moxifloxacin requires only three times daily dosing versus four times daily for polymyxin B/trimethoprim 6, 7

Azithromycin vs. Tobramycin

• Azithromycin 1.5% produces significantly greater improvement in conjunctival discharge (P<0.01) and more frequent complete resolution at day 3 (P=0.005) 5
• Parents found azithromycin easier to use due to shorter treatment duration (3 days vs. 7 days) 5

Natural History with Topical Antibiotics

• Topical antibiotics shorten disease duration: 62% clinical cure at 3-5 days with polymyxin-bacitracin versus 28% with placebo (P<0.02) 4
• Bacterial eradication occurs in 71% by day 3-5 with antibiotics versus 19% with placebo (P<0.001) 4

Critical Follow-Up and Referral Criteria

When to Reassess

• Return for follow-up if no improvement after 3-4 days of treatment 1, 2
• Perform interval history, visual acuity measurement, and slit-lamp biomicroscopy at follow-up 1

When to Refer to Ophthalmology

• Immediate referral required for: visual loss, moderate or severe pain, severe purulent discharge, corneal involvement, conjunctival scarring, lack of response to therapy, or recurrent episodes 1, 2
• Hospitalization mandatory for neonatal conjunctivitis 1

Important Pitfalls and Caveats

• Do not prescribe antibiotics for viral conjunctivitis - this accounts for unnecessary costs and promotes resistance 1
• Avoid tapering below 3-4 times daily before completing the full course as subtherapeutic dosing increases resistance risk 2
• Consider sexual abuse in children with gonococcal or chlamydial conjunctivitis 10, 1
• Bacterial resistance is a growing concern, particularly with MRSA infections, and poor adherence to frequent administration regimens contributes to treatment failure 1
• Povidone-iodine 1.25% ophthalmic solution may be as effective as topical antibiotics and can be considered when access to antibiotics is limited 1